How do I adjust the size of axes labels and figure titles in plots?

edit

I've been experimenting around with the following code:

from sage.calculus.desolvers import desolve_odeint
y,dy = var('y,dy');
g    = 9.8; 
l    = 1; 
f    = [dy,-g/l*cos(y)];
v    = [y,dy];
t    = srange(0,5,0.01);
ci   = [0,0];
sol  = desolve_odeint(f,ci,t,v,rtol=1e-15, atol=1e-10,h0=1e-4,hmax=1e-2,hmin=1e-6,mxstep=10000)
p    = line(zip(t,sol[:,0]),title=r"$\frac{d^{2}\theta}{dt^2} = -\frac{g}{l} \cos{\theta}$",axes_labels=[r"$t$",r"$\theta$"]);
p2   = line(zip(t,sol[:,1]));
p2  += text(r"$\frac{d\theta}{dt}$",(-0.5,0),fontsize=27);
p2  += text(r"$t(s)$",(5,0.5),fontsize=20);
p.show()

which gives this plot:

As you can see the axes labels and title of the figure are insanely small (or at least in my opinion). I'd like the axes labels to be 20 pt and the figure title to be 30 pt. How do I do this?